Saturable reactor devices



Jan. 26, 1960 L. D. DE LALlo 2,922,946

SATURABLE REAcToR DEVICES Filed Dec. 19, 1955 4Z f6 1.9 la

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gigi i nfl INVENTQR ATTORNEY United States Patent O 2,922,946 SATURABLEREACTOR DEVICES Louis D. De Lalio, Huntington, N.Y., assignor to SperryRand Corporation, a corporation of Delaware Application December 19,1955, Serial No. '553,811 2 Claims. (Cl. 323-89) The present inventionvices.

Saturable reactor devices are known in the art for providing a full waveor a half wave output in response to a signal input control voltage.Since the output of a full wave device in response to a signal inputthereto occurs relates to saturable reactor depower provided by a fullwave device might be sutiicient.

However, a conventional full wave magnetic amplifier generally has atleast four inductive control windings in series with each other, andtherefore, an input control signals so that the speed 2,922,946 PatentedJan. 26, 1960 with a load coupled to both stages. Control voltageWindings are provided in the driver stage for receiving an input controlsignal. Control voltage windings are further provided with `the rivenstage,

and material and lar hysteresis or B*H loops. Y

A rst or driver stage of the device is comprised of four similar powerwindings 16-19 connected in a bridge type circuit between the outputterminals 21 and 22, of

a frequency of the order of 400 cycles example. Alternate windings 16and therethrough to occur. opposite directions from rectitiers 25-28 sothat the first stage of the device operates on the opposite half cycleof such a voltage. Biaswindings 41-44-connected in series with aresistor 46 and a pair of terminals for receiving a direct currentbiasing voltage Ec are disposed about the reactor cores respectively,for setting the reference magnetic flux level of each of the cores.v Thebiasing current 41-44 is regulated so that the cores 11 andr12 are setto the same reference magnetic flux level by a negative magnetizingforce and thecores 13 and 14 are set to the vsame reference magnetic uxlevel by a positive` magnetizing force, for example. Y VA pair or'controlV windings 47 and 48 are connected in series with a pair of inputterminals`51 and 52 for receiving a suitable control signal voltage forthe device. The control windings 47 and 48 are disposed upon cores 11and 12 of the first stage of the device and wound so that a signalvoltage at any particular time between terminals 51-52 will cause themagnetic linx level of each of the cores 11 and 12 to be changed inVopposite directions.` A further pair of control windings 53 and 54 forthe second stage of the device are connected together in series anddisposed about the cores 13 and 14 and wound so that'a voltage at anyparticular time across windings 534-54 each of cores 13 and 14 to changein opposite directions. An end terminal of thecontrol winding 53 isconnected to the junction point between the rectiers 25 and 26. An rendterminal of the control winding 54 is connected to the junction pointbetween the rectiiers 38 and 39. A suitable load 56 has one terminalconnected -to the aforementioned junction point between rectiers 27 and28 and to the junction point between rectiers 36 and 37. vThe otherterminal of load 56 is connected to the junction point betweenrectiiiers 38 and 39. Thus, the load'56 is effectively in series withoutput terminals for each half wave stages in Fig. l. The exact natureof load 56 is a function of the use for which the reactor device isadapted. If the device is to be used as an A.C. amplifier, the load 56might comprise a two phase A.C.

servomotor, for example.

In operation of the device shown in Fig.Y l, iirst assume that there isno control voltage applied to terminals Y51 and 52, that the source 23is not supplying a power voltage to the device, and that the biaswindings 41-44 are receiving a bias voltage Ecof the polarity indicatedin Fig. l. It the turns of the windings 41-44 are properly regulated,the cores 11-14 can be magnetized to the fsame reference flux level withthe cores 11 and 12 being magnetized by a negative one direction and thecores 13 and 14 by a positive magnetizing force +II in the oppositedirection. Each of the cores 11-14 BLH loop generally like therectangular hysteresis loop shown in Fig. 2, which is a plot of themagnetic flux density B for each core as a function of the magnetizingforce Happlied thereto. The cores 11 and 12 might be biased by windings41,-42 to a flux level designated by point e on the B-H loop of Fig. 2with the cores 13 and 14 being biased by the windings 43--44 to areference flux level designated by point f on the aforementioned loop,for example.

Assumevnow that a sine wave alternating voltage is supplied by thesource 23 to the Iterminals 21 and 22. If the terminal 21 is positivewith respect to the terminal -22 on the tirst half cycle of this powersupply voltage,

the rectiiiers 25-28 in the iirst stage of the device will conduct andpower supply current will ow through the power windings 16-19. If therehad been no control voltage signal applied to the terminals 51 and 52,the cores 11 and 12 would have previously been biased to the Vsarnereference flux level designated by point e on the hysteresis loop shownin Fig. 2. The magnetizing cur- 'rent through windings 16-19 is in sucha direction that the ux density in the cores 11 and 12 goes positive. Atsome time duringkthe aforementioned halt cycle of the voltage fromsource 23 at a phase angle of approximately 90, for example (which isdetermined by proper design of the system), the cores 11 and 12 can bemade to lire simultaneously due to magnetic saturation thereof by themagnetizing iield of the power current through the windings 16-19. Thiswill greatly lower th@ inductive immight have a magnetization curve orwill cause the magnetic ilux level of magnetizing force--H in "aeaaasefA but will not upset the which such windings are 12 were simultaneouslypedance Z1 of windings 16-19, balance of the bridge circuit in includedsince the cores 11 and saturated. Thus, there will tween the junction ofof rectiers 27-28 and no voltage is supplied toload 56 and the secondstage ofthe device.

At the end of the aforementioned rst half cycle of the voltage fromsource 23, the cores 11 and 12 will remain at a positive +B residualmagnetismretained therein. However, on the succeeding half cycle of thevoltage from source '23 when the terminal 21 isnegative with respect tothe terminal 22 Vso that there is no current iiow through power`windings 16-19, the current through biasing windings 41 and 42 willcause the cores 11 and 12 to return to their initial states ofmagnetization at point e on the B-H loop ofvl"ig.2.A Y .Y Y f `On theaforementioned succeeding half cycle ofthe voltage from source 23whenrthe terminal 22 goes positive with respect to the terminal 21, therectiers 36-39 in the next stage of the device will be conductive. lfthe operating characteristics ,of the device are properly chosen, thecores 13 and 14 can be saturated ata phase angle of 27G,for example, ofthe power supply voltage from source '23 during this succeeding halfcycle, for example. Power current through windings 31-34 isin such adirection that the ux density for cores 13 and 14 goes negative. Sincethere was no control voltage previously applied to the control windings53 and 54 during the previous half cycle ot the voltage from source 23,the cores 13 and 14 will also be saturated and fired simultaneously.Saturation is at a -B magnetic saturation level in Fig.p2'.

There will be no change in voltage betweenthe junction lot rectiers36-37 and the junction of rectitiers 38-'39 if cores 13 and 14 are firedsimultaneously. On the next half cycle of the voltage from source 23after the second stage of the device is iinished conducting, the

Ycores 13 and 14 are returned to their original state of Assume now thata small D.C. control voltage signal is applied between the terminals 51and'52 with terminalV 51 positive with respect to terminal 52. Duringthe half cycle of. the voltage from source 23 when the windings 16-19are not conducting, the iiux level of the core 11 will only go downfrom' a +B saturation level to point g on the BV-H loop of Fig. 2'whilethe flux level of core 12 will go further down on the B-H loop to pointj; This occurs since the control current travels through the controlwindings 47 and 48 in opposite directions at any particular time andwhen terminal 51 is positive with respect to terminal 52, the directionof the current is such that Ythe magnetizing force provided therebyopposes thenegative magnetizing force applied to core 11V by biaswinding 41 the negative magnetizing force applied to core 12 by biaswinding 42. `On the' following half cycle of the voltage from source 23when the power windings 16-19 are conducting, it can readily be seenYthat the core 11 will be returned to a +B Vsaturation level before core12 so as to unbalance the bridge circuit vcomprised of windings 16-19.During the time-the bridge circuit compriSing windings 16-19 isunbalanced, a voltage is provided between thejunction of rectiers 25'-26and the junction of rectifier-s 27--28.Y Thisvoltage is supplied to theload 56 and to the control windings 53 and 54 of the second stage of thedevice shownin Fig. l.

The `aforementioned voltage supplied to 53 and 54 and currenttherethrough directed magnetizing forces Afor cores provide oppositely13 and 14 so that the core 13 is'magnetized to'a ux level designated bypoint min Fig.v 2 and the core 14 is magnetized to the be no voltagedifference berectifiers 25--26 andthe junction Y magnetic saturationlevel due to theand raids the windings i level designated by point kduring the non-conducting half cycle for power windings 31-34, each ofcores 13 and 14 having previously lbeen at as a result of If an A.C.control voltage were applied to the terminals 51 and 52 in the device ofFig. 1, the control voltage being in phase with or 180 out of phase withsignal voltage input. would reverse with a reversal in phase of analternating input signal control 51 and 52.

to y corresponding primed reference numerals 1n Fig 3. e difference inthe circuit shown in Fig 3 from that of of the control windings of theconnecting windings 53 54 in series of the rst stage, they areeffectively connected in parallel across fthe load 56' (the output ofthe first stage).

dn'ven stage. Instead of with the output A magnetic amplifierarrangement for producing a full-wave output from a half-wave inputcontrol signal, comprising a source of alternating current, a iirstfirst stage whereby said rst stage delivers to said load yan outputvoltage correlative to said control signal on the conductive half-cycleof said irst stage, said rst and output voltage which livered by thefirst stage on the preceding half-cycles of the alternating currentsource.

References Cited in the le of this patent UNITED STATES PATENTS2,169,093 Edwards Aug. 8, 1939 2,734,165 Lufcy et al. Feb. 7, 19562,754,474 Barnhart July 10, 1956

